AxBAx-type block-graft polymers with soft methacrylate middle segments and hard styrene outer grafts: Synthesis, morphology, and mechanical properties

Yu Miura, Takeshi Kaneko, Kotaro Satoh, Masami Kamigaito, Hiroshi Jinnai, Yoshio Okamoto

Research output: Contribution to journalArticlepeer-review

16 Citations (Scopus)

Abstract

Novel copolymers with controlled architectures can function as new building blocks for well-defined nanostructures on the basis of micro-phase separation, unlike conventional ABA triblock copolymers. A series of well-defined A xBAx-type block-graft copolymers consisting of soft middle segments (dodecyl methacrylate (DMA)) and hard outer graft chains (styrene (St)) were synthesized by ruthenium-catalyzed living radical block and graft polymerization. NMR spectroscopy and size-exclusion chromatography combined with multiangle laser light scattering confirmed the well-defined structure of the AxBAx block-graft copolymers with backbones and graft chains of controlled lengths. Transmission electron microscopy and transmission electron microtomography revealed a series of morphologies for the copolymers. Morphological changes were observed from PSt "honeycomb" cylinders to lamellae and poly(DMA) cylinders with increasing PSt-graft content, whereby the phase diagram was shifted significantly to lower volume fractions of the larger-number component (St) relative to those of the corresponding ABA triblock copolymers. More specifically, poly(DMA) cylinders were observed even before the St content reached 50wt%. The AxBAx and ABA copolymers with 17-30 wt% of St exhibited characteristics of a thermoplastic elastomer with tensile strengths of 1-6 MPa and elongations at break of 70-300%. These mechanical properties can be related well to the microphase structures of the AxBAx and ABA copolymers.

Original languageEnglish
Pages (from-to)662-672
Number of pages11
JournalChemistry - An Asian Journal
Volume2
Issue number5
DOIs
Publication statusPublished - 2007 Jul 2
Externally publishedYes

Keywords

  • Block copolymers
  • Mechanical properties
  • Nanostructures
  • Polymerization
  • Ruthenium

ASJC Scopus subject areas

  • Biochemistry
  • Organic Chemistry

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